The basic operation and structure of trunking communication systems and cellular telephone communication systems (cellular communication systems) are known. Trunking communication systems typically comprise a communication channel controller, a limited number of repeaters that transceive information via communication channels, and a plurality of communication units which may be mobile vehicle radios and/or portable radios and may also include data transmission features. Of the communication channels, one is typically chosen to be a control channel. The control channel typically transceives operational information between the communication channel controller and the data transmission features of the plurality of communication units such that, for example, the plurality of communication units can access the communication channels. Typically, the trunking system has a relatively large geographic coverage area, depending on the environment that the trunking communication system is located, for example, the coverage area may be approximately thirty-five miles in diameter.
A cellular communication system typically comprises a mobile telephone switching office (MTSO), a plurality of cells, a limited number of communication channels, and a plurality of communication units which may be cellular telephones. Each of the plurality of cells comprises some of the limited number of communication channels, wherein one of the communication channels is designated as the control channel for that cell. The control channel transceives operational information between the plurality of communication units within the cell and the MTSO such that the communication units can place telephone calls via a phone system. Typically, the coverage area of each cell is relatively small in comparison with that of a typical trunking communication system. For example, a typical cell coverage area is approximately two miles in diameter. Because an individual cell coverage area is relatively small, the communication channels may be reused, at least once, with in a geographic region of approximately the same size as a trunking communication system.
In trunking communication systems, data may be transmitted, on the control channel, from the communication channel controller to the plurality of communication units. Such data transmissions cause data traffic on the control channel and in many instances reduce the overall efficiency of the trunking communication system. For example, during a dynamic regrouping of communication units, each communication unit must be addressed individually due to unique features of the communication unit. (Unique features of a communication unit may include priority calling, secure calling, private calling, etc.) Dynamic regrouping for large groups-of fifty communication units or more-typically requires a substantial amount of time-at least several seconds-to regroup the communication units.
In addition to receiving data from the communication channel controller, each of the plurality of communication units may individually transmit data to the communication channel controller. Data transmissions from a communication unit to the communication channel controller is also transmitted on the control channel of the trunking communication system which further adds to the data traffic. Such point to point data transmissions in the trunking communication system are relatively inefficient due to the limited number of communication channels used as control channels. (Typically, only one communication channel is designated as a control channel, thus all data transceived within the trunking communication system must be transceived over that control channel.) Cellular communication systems, however, are relatively efficient at processing point to point data transmissions due to the relatively large number of control channels; at least one for each cell of the cellular communication system where data transmissions in the cellular communication system include, for example, placing telephone calls.
Therefore, a need exists for a method that allows a trunking communication system to take advantage of the communication channel efficiency of a cellular communication system for point to point, or private, data transmissions.